A method for separating platinum metal from spent platinum catalyst
By combining ultrasonic-pulsed electric field synergistic leaching and modified MOF material adsorption with hydrazine hydrate reduction, the problems of high equipment wear and the inability to recycle the carrier in existing technologies are solved, achieving efficient and low-cost platinum metal recovery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HEFEI UNIV
- Filing Date
- 2026-01-21
- Publication Date
- 2026-06-26
AI Technical Summary
Existing methods for separating platinum metal from waste platinum catalysts suffer from problems such as high equipment wear and tear, high wastewater treatment costs, or the inability to recycle the carrier.
Platinum powder was leached using a mixed leaching agent under an ultrasonic-pulsed electric field environment. Platinum ions were then adsorbed using a modified MOF material, reduced by hydrazine hydrate, and finally washed with dilute nitric acid to obtain platinum powder, thus protecting the carrier and improving the recovery efficiency.
It achieves efficient leaching and selective separation of platinum metal, reduces energy consumption and pollution, and allows the carrier to be recycled, significantly reducing recycling costs.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of resource utilization technology, and specifically to a method for separating platinum metal from waste platinum catalysts. Background Technology
[0002] Platinum (Pt), as a key precious metal, is widely used in catalysts for automotive exhaust purification, petrochemical hydrogenation, and pharmaceutical synthesis. With catalyst deactivation (such as carbon buildup and sintering of active components), a large amount of waste platinum catalyst is generated, typically containing 0.1 wt% to 5 wt%, which has extremely high recycling value.
[0003] Currently, the mainstream recycling methods mostly use aqua regia, high-concentration hydrochloric acid-chlorate (such as NaClO3), or alkaline melting (such as Na2O2 melting). The former, with its strong acid reagents, leads to high equipment wear and high wastewater treatment costs, while the latter directly destroys the structure of carriers such as Al2O3, making it impossible to achieve carrier recycling. Summary of the Invention
[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for separating platinum metal from waste platinum catalysts, which aims to solve the technical problems of high equipment wear and high wastewater treatment costs or the inability to achieve carrier recycling in the prior art, which uses strong acid reagents or alkali melting methods.
[0005] One aspect of this invention is to provide a method for separating platinum metal from spent platinum catalyst, the method comprising:
[0006] Waste platinum catalyst is pulverized to 80-120 mesh and calcined at a first preset temperature to remove surface organic matter, thus obtaining waste platinum powder.
[0007] Waste platinum powder is added to a mixed leaching agent according to a preset solid-liquid ratio. The leaching temperature is adjusted under an ultrasonic-pulse electric field environment, and the solution is filtered to obtain a leachate. The mixed leaching agent includes hydrochloric acid, sodium sulfite, and citric acid.
[0008] Modified MOF material was added to the leachate to adjust the pH value, adsorb platinum ions, and then filtered to obtain filter residue.
[0009] The filter residue is added to the desorption solution for analysis, filtered, and hydrazine hydrate is added to the filtrate. The filtrate is then reduced at a second preset temperature, and solid-liquid separation is performed to obtain sponge platinum. The desorption solution includes thiourea and hydrochloric acid.
[0010] The platinum sponge was washed with dilute nitric acid and dried under vacuum to obtain platinum powder.
[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: The method for separating platinum metal from waste platinum catalyst provided by the present invention achieves efficient leaching of platinum metal while effectively protecting the carrier through the synergistic effect of the mixed leaching agent ternary leaching agent, and further improves the leaching efficiency by combining ultrasonic-pulsed electric field synergistic enhancement of mass transfer; the specific adsorption sites of the modified MOF material solve the problem of selective separation of platinum metal and impurity ions, greatly improving the recovery purity; and the efficient reduction of platinum metal is achieved through desorption and hydrazine hydrate, with low energy consumption and low pollution. Moreover, the MOF material can be recycled, greatly reducing the recycling cost. Thus, the present invention solves the technical problems of the prior art that use strong acid reagents or alkali melting methods, resulting in high equipment wear, high wastewater treatment costs, or inability to achieve carrier recycling.
[0012] According to one aspect of the above technical solution, the first preset temperature is 150℃~200℃, and the calcination time is 40min~60min.
[0013] According to one aspect of the above technical solution, waste platinum powder is added to a mixed leaching agent according to a preset solid-liquid ratio, and leaching is performed under an ultrasonic-pulsed electric field environment with adjusted leaching temperature. The mixture is then filtered to obtain a leachate. The mixed leaching agent comprises hydrochloric acid, sodium sulfite, and citric acid. Specifically, the steps include:
[0014] Waste platinum powder is added to the mixed leaching agent according to a preset solid-liquid ratio and stirred evenly. The mixed leaching agent includes 0.8mol / L~1.2mol / L hydrochloric acid, 0.4mol / L~0.6mol / L sodium sulfite, and 0.2mol / L~0.4mol / L citric acid. The solvent is water, and the preset solid-liquid ratio is 1g:(10~15)mL.
[0015] The solution is then added to a coupled reactor that integrates an ultrasonic generator and a high-voltage pulse power supply. It is then leached for 30 to 50 minutes under an environment with an ultrasonic power of 250W to 350W, a pulse electric field strength of 12kV / m to 18kV / m, a pulse frequency of 40Hz to 60Hz, a leaching temperature of 50℃ to 70℃, and a stirring rate of 150rpm to 250rpm. The solution is then filtered to obtain the leachate.
[0016] According to one aspect of the above technical solution, the modified MOF material includes UiO-66-ATU, and its preparation method includes:
[0017] Add 5g~15g of UiO-66-NH2 to 450mL~550mL of DMF according to the solid-liquid ratio and disperse ultrasonically for 20min~40min to obtain a suspension;
[0018] Add 2g~5g of 3-aminothiourea and 0.5g~3g of N,N'-dicyclohexylcarbodiimide to the suspension, stir the mixture at 50℃~70℃, at a stirring rate of 100rpm~200rpm, for 6h~10h, filter, and wash the filter cake three times alternately with DMF and anhydrous ethanol.
[0019] UiO-66-ATU was obtained by drying at 50℃~70℃ for 10h~15h.
[0020] According to one aspect of the above technical solution, the solid-liquid ratio of the modified MOF material to the leachate is 1g:(0.1~0.4)L, the pH value is 2~3, and the pH value adjuster is hydrochloric acid.
[0021] According to one aspect of the above technical solution, the adsorption step includes:
[0022] Placed in a constant temperature oscillation environment, adsorbed for 40 min to 60 min at a oscillation rate of 200 rpm to 250 rpm at a temperature of 20 ℃ to 40 ℃.
[0023] According to one aspect of the above technical solution, the mass ratio of the filter residue to the desorption solution and hydrazine hydrate is 1:(20~45):(0.05~0.2), and the desorption solution includes 0.05mol / L~0.2mol / L hydrochloric acid, 0.1mol / L~0.5mol / L thiourea, and water as the solvent.
[0024] According to one aspect of the above technical solution, the desorption step includes:
[0025] Desorption was carried out by stirring at 30℃~40℃, with a stirring rate of 150rpm~250rpm and a stirring time of 20min~30min.
[0026] According to one aspect of the above technical solution, the second preset temperature is 60℃~80℃, the reduction time is 20min~50min, the reduction stirring rate is 150rpm~250rpm, and the solid-liquid separation conditions are centrifugation at 2500rpm~3500rpm for 4min~10min.
[0027] According to one aspect of the above technical solution, the concentration of dilute nitric acid is 3wt%~7wt%, and the vacuum drying conditions are vacuum drying at 70℃~90℃ for 1.5h~3h. Detailed Implementation
[0028] To make the objectives, features, and advantages of this invention more apparent and understandable, the invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this invention will be thorough and complete.
[0029] This invention provides a method for separating platinum metal from spent platinum catalysts, the recovery method comprising: steps S10-S14,
[0030] Step S10: The waste platinum catalyst is crushed to 80-120 mesh and calcined at a first preset temperature to remove surface organic matter and obtain waste platinum powder.
[0031] The first preset temperature is 150℃~200℃, and the calcination time is 40min~60min to remove organic matter (such as carbon deposits and oil stains) attached to the catalyst surface. Secondly, low-temperature calcination combined with pulverization ensures that the carrier is retained while removing organic matter, avoiding high temperature (>300℃) that causes Al2O3 carrier crystal transformation or carbon carrier combustion, resulting in subsequent carrier leaching, thereby affecting platinum recovery.
[0032] In addition, the method further includes: before leaching, stirring and leaching with sodium hydroxide (NaOH) solution (2mol / L~4mol / L) at 80℃~90℃ for 1h~2h to generate soluble sodium stannate, separating the solid and liquid to remove tin and other metal impurity ions, and then adding the filter residue to an ammonia mixed solution (4mol / L~6mol / L ammonia water, 1mol / L~2mol / L NH4Cl) at a solid-liquid ratio of 1g:(10~15)mL, stirring and leaching at 60℃~80℃ for 0.5h~2h to generate a soluble palladium complex, filtering to remove palladium and other metal impurity ions, washing the filter residue with water, and drying to obtain waste platinum powder.
[0033] Step S11: Add waste platinum powder to the mixed leaching agent according to the preset solid-liquid ratio, leach under the ultrasonic-pulse electric field environment, adjust the leaching temperature, filter, and obtain leachate. The mixed leaching agent includes hydrochloric acid, sodium sulfite, and citric acid.
[0034] Specifically, waste platinum powder is added to a mixed leaching agent according to a preset solid-liquid ratio and stirred evenly. The mixed leaching agent includes 0.8 mol / L to 1.2 mol / L hydrochloric acid, 0.4 mol / L to 0.6 mol / L sodium sulfite, and 0.2 mol / L to 0.4 mol / L citric acid. The solvent is water, and the preset solid-liquid ratio is 1 g: (10~15) mL.
[0035] It should be noted that sodium sulfite is easily decomposed in hydrochloric acid solution. Citric acid, as a weak organic acid, can buffer the pH of the system, mitigating the severe impact of hydrochloric acid solution on sodium sulfite, thereby effectively inhibiting or reducing the escape of sulfur dioxide gas. Secondly, in hydrochloric acid medium, sodium sulfite can selectively oxidize Pt(0) in waste platinum catalyst to Pt(IV), while citric acid forms a stable [Pt(C6H5O7)2] with Pt(IV). 2-Complexes (avoiding Pt(IV) hydrolysis and precipitation), on the other hand, through complexation of Al 3+ (Forms [Al(C6H5O7)]) 0 Inhibiting the dissolution of the Al2O3 support, that is, when Al2O3 just dissolves, a small amount of Al is produced. 3 + It is immediately complexed and consumed by citric acid, and there is never a sufficient amount of free Al in the solution. 3+ Pushing the balance to move in the positive direction, but instead due to Al 3+ The driving force for Al2O3 dissolution (i.e., replenishment of Al) remains locked. 3+ The demand for Al2O3 is weakened, making it difficult for the Al2O3 support to dissolve further.
[0036] The solution is then added to a coupled reactor that integrates an ultrasonic generator and a high-voltage pulse power supply. It is then leached for 30 to 50 minutes under an environment with an ultrasonic power of 250W to 350W, a pulse electric field strength of 12kV / m to 18kV / m, a pulse frequency of 40Hz to 60Hz, a leaching temperature of 50℃ to 70℃, and a stirring rate of 150rpm to 250rpm. The solution is then filtered to obtain the leachate.
[0037] Furthermore, the ultrasonic cavitation effect disrupts the boundary layer on the surface of the waste platinum catalyst, promoting the diffusion of the leaching agent; the pulsed electric field accelerates the migration of the Pt(IV)-citric acid complex, and the two work synergistically to improve the platinum leaching rate.
[0038] Step S12: Add modified MOF material to the leachate, adjust the pH value, adsorb platinum ions, filter, and obtain filter residue;
[0039] Modified MOF materials include UiO-66-ATU, and their preparation methods include:
[0040] Add 5g~15g of UiO-66-NH2 to 450mL~550mL of DMF according to the solid-liquid ratio and disperse ultrasonically for 20min~40min to obtain a suspension;
[0041] Add 2g~5g of 3-aminothiourea and 0.5g~3g of N,N'-dicyclohexylcarbodiimide to the suspension, stir the mixture at 50℃~70℃, at a stirring rate of 100rpm~200rpm, for 6h~10h, filter, and wash the filter cake three times alternately with DMF and anhydrous ethanol.
[0042] UiO-66-ATU was obtained by drying at 50℃~70℃ for 10h~15h.
[0043] It should be noted that by grafting 3-aminothiourea (ATU) onto UiO-66-NH2 and introducing thiourea groups via a carbamate reaction, the -SH and -NH2 groups in ATU can form specific coordination bonds (Pt-S and Pt-N) with Pt(IV), increasing the selectivity for Pt(IV). Through the synergy of the high specific surface area of the MOF material and the specific ligands of ATU, rapid and highly selective adsorption of Pt(IV) is achieved with strong anti-interference capabilities, eliminating the need for complex subsequent corrections. Furthermore, -SH (soft base) and -NH2 (medium soft base) form stable Pt-S / Pt-N coordination bonds with Pt(IV) (soft acid), while for Fe... 3+ (Hard acid), Al 3+ (Hard acid), Cu 2+ (Boundary acid) has extremely weak coordination ability.
[0044] Furthermore, the solid-liquid ratio of the modified MOF material to the leachate is 1 g: (0.1~0.4) L, the pH value is 2~3, and the pH value adjuster is hydrochloric acid.
[0045] Under pH conditions of 2-3, the amino groups (-NH2) on the surface of UiO-66-ATU material will be partially protonated, forming positively charged -NH groups. 3+ Pt(IV) is represented by [Pt(C6H5O7)2]. 2- It exists in a stable state, with positively charged UiO-66-ATU and negatively charged [Pt(C6H5O7)2]. 2- Electrostatic attraction occurs between them. Upon approaching, the strong coordination between Pt(IV) and the thiourea group (-SH) on UiO-66-ATU becomes dominant, achieving a stable bond. Therefore, its binding priority with UiO-66-ATU is much higher than that of other ions or Fe. 3+ / Al 3+ Hydroxyl complexes formed (such as Fe(OH)2) + This will enhance the selectivity of the modified MOF material and further suppress competition from non-target ions.
[0046] Further, the adsorption step includes:
[0047] Placed in a constant temperature oscillation environment, adsorbed for 40 min to 60 min at a oscillation rate of 200 rpm to 250 rpm at a temperature of 20 ℃ to 40 ℃.
[0048] In addition, the filtrate obtained by filtration can be subjected to vacuum distillation to recover hydrochloric acid. The remaining residue is then added with excess sodium metabisulfite and heated (60℃~80℃) to reduce sodium sulfate to sodium sulfite. After vacuum concentration (70℃~80℃, -0.08MPa), the filtrate is cooled to crystallize and obtain sodium sulfite crystals, which are then filtered, washed with ice water, dried and recovered.
[0049] An alkaline regulator is added to the citric acid mother liquor after filtration of the residual liquid to precipitate metal ions, and other metal ions are then recovered by filtration.
[0050] Step S13: Add the filter residue to the desorption solution for analysis, filter, add hydrazine hydrate to the filtrate, reduce at a second preset temperature, separate the solid and liquid, and obtain sponge platinum. The desorption solution includes thiourea and hydrochloric acid.
[0051] The mass ratio of the filter residue to the desorption solution and hydrazine hydrate is 1:(20~45):(0.05~0.2). The desorption solution includes 0.05mol / L~0.2mol / L hydrochloric acid and 0.1mol / L~0.5mol / L thiourea, and the solvent is water.
[0052] Furthermore, the desorption step includes:
[0053] Desorption was carried out by stirring at 30℃~40℃, with a stirring rate of 150rpm~250rpm and a stirring time of 20min~30min.
[0054] It should be noted that thiourea is a strong complexing agent, and its addition completely alters the system, enabling it to form a more stable soluble complex with platinum (Pt(IV)) [Pt(SC(NH2)2)4] than UiO-66-ATU. 2+ This process removes platinum from the UiO-66-ATU surface, transforming it into positively charged ions. The UiO-66-ATU surface remains protonated and positively charged (-NH). 3+ The newly formed positively charged platinum-thiourea complex generates a strong electrostatic repulsion force with the positively charged UiO-66-ATU surface. Under the combined effect of stronger coordination competition and electrostatic repulsion, the platinum is efficiently pushed away from the UiO-66-ATU surface and enters the solution, thus achieving desorption.
[0055] In addition, the filter residue obtained from the vacuum filtration was washed with water and then vacuum dried at 60°C for 8 hours to restore the porous structure, yielding UiO-66-ATU, which was used for the next batch of adsorption.
[0056] Furthermore, the second preset temperature is 60℃~80℃, the reduction time is 20min~50min, the reduction stirring rate is 150rpm~250rpm, and the solid-liquid separation conditions are centrifugation at 2500rpm~3500rpm for 4min~10min.
[0057] In addition, hydrazine hydrate is added slowly dropwise. Thiourea acts as a bridging ligand, and its strong coordination effect shields the core positive charge of Pt(IV), which greatly weakens the overall electrostatic repulsion, promotes electron transfer between hydrazine hydrate and Pt(IV), and enhances the reduction reaction.
[0058] Step S14: Wash the sponge platinum with dilute nitric acid and dry it under vacuum to obtain platinum powder.
[0059] The concentration of dilute nitric acid is 3wt%~7wt% to remove residual thiourea and other metal elements. The vacuum drying conditions are vacuum drying at 70℃~90℃ for 1.5h~3h.
[0060] The present invention is further illustrated below with specific embodiments:
[0061] Example 1
[0062] The first embodiment of the present invention provides a method for separating platinum metal from waste platinum catalyst, the recovery method comprising: steps S10-S14,
[0063] Step S10: The waste platinum catalyst is crushed to 80-120 mesh and calcined at a first preset temperature to remove surface organic matter and obtain waste platinum powder.
[0064] The sieve has a mesh size of 100, the first preset temperature is 180℃, and the calcination time is 50min.
[0065] In addition, the method further includes: before leaching, stirring and leaching with sodium hydroxide (NaOH) solution (3mol / L) at 85°C for 1.5h to separate solid and liquid, then adding the filter residue to an ammonia mixed solution (5mol / L ammonia water, 1.5mol / L NH4Cl) at a solid-liquid ratio of 1g:12mL, stirring and leaching at 70°C for 1h, filtering, washing the filter residue with water, and drying to obtain waste platinum powder.
[0066] Step S11: Add waste platinum powder to the mixed leaching agent according to the preset solid-liquid ratio, leach under the ultrasonic-pulse electric field environment, adjust the leaching temperature, filter, and obtain leachate. The mixed leaching agent includes hydrochloric acid, sodium sulfite, and citric acid.
[0067] Specifically, waste platinum powder is added to a mixed leaching agent according to a preset solid-liquid ratio and stirred evenly. The mixed leaching agent includes 1.0 mol / L hydrochloric acid, 0.5 mol / L sodium sulfite, and 0.3 mol / L citric acid. The solvent is water, and the preset solid-liquid ratio is 1g:12mL. 100g of waste platinum powder is added to 1200mL of the mixed leaching agent.
[0068] The solution was then added to a coupled reactor that integrates an ultrasonic generator and a high-voltage pulse power supply. It was then leached for 40 minutes under an environment with an ultrasonic power of 300W, a pulse electric field strength of 15kV / m, a pulse frequency of 50Hz, a leaching temperature of 60℃, and a stirring rate of 200rpm. The solution was then filtered to obtain the leachate.
[0069] Step S12: Add modified MOF material to the leachate, adjust the pH value, adsorb platinum ions, filter, and obtain filter residue;
[0070] Modified MOF materials include UiO-66-ATU, and their preparation methods include:
[0071] 10g of UiO-66-NH2 was added to 500mL of DMF according to the solid-liquid ratio and ultrasonically dispersed for 30min to obtain a suspension;
[0072] Add 3.5g of 3-aminothiourea and 1.2g of N,N'-dicyclohexylcarbodiimide to the suspension, stir at 60℃ for 150rpm for 8h, filter, and wash the filter cake three times alternately with DMF and anhydrous ethanol.
[0073] UiO-66-ATU was obtained by drying at 60℃ for 12 hours.
[0074] Furthermore, the modified MOF material is added in an amount of 5g, the pH value is 2.5, and the pH value adjuster is hydrochloric acid.
[0075] Further, the adsorption step includes:
[0076] Placed in a constant temperature oscillator, it was adsorbed for 50 min at 30℃ and an oscillation rate of 250 rpm.
[0077] Step S13: Add the filter residue to the desorption solution for analysis, filter, add hydrazine hydrate to the filtrate, reduce at a second preset temperature, separate the solid and liquid, and obtain sponge platinum. The desorption solution includes thiourea and hydrochloric acid.
[0078] The amount of desorption solution added is 200 mL, which includes 0.1 mol / L hydrochloric acid, 0.2 mol / L thiourea, and water as the solvent.
[0079] Furthermore, the desorption step includes:
[0080] Desorption was carried out by stirring at 35°C at a stirring rate of 200 rpm for 25 min.
[0081] Furthermore, the second preset temperature is 70℃, the reduction time is 35min, the reduction stirring rate is 200rpm, and the solid-liquid separation condition is centrifugation at 3000rpm for 5min.
[0082] Furthermore, the amount of hydrazine hydrate added was 0.8g, and the method of addition was slow dripping.
[0083] Step S14: Wash the sponge platinum with dilute nitric acid and dry it under vacuum to obtain platinum powder.
[0084] The concentration of dilute nitric acid is 5 wt%, and the vacuum drying conditions are vacuum drying at 80°C for 2 hours.
[0085] Example 2
[0086] The second embodiment of the present invention provides a method for separating platinum metal from waste platinum catalyst. The method for separating platinum metal from waste platinum catalyst in this embodiment differs from the method for separating platinum metal from waste platinum catalyst in the following ways:
[0087] The mixed leaching agent includes 0.8 mol / L hydrochloric acid, 0.6 mol / L sodium sulfite, and 0.3 mol / L citric acid.
[0088] Example 3
[0089] The third embodiment of the present invention provides a method for separating platinum metal from waste platinum catalyst. The method for separating platinum metal from waste platinum catalyst in this embodiment differs from the method for separating platinum metal from waste platinum catalyst in the following ways:
[0090] The mixed leaching agent comprises 1.2 mol / L hydrochloric acid, 0.4 mol / L sodium sulfite, and 0.4 mol / L citric acid.
[0091] Example 4
[0092] The fourth embodiment of the present invention provides a method for separating platinum metal from waste platinum catalyst. The method for separating platinum metal from waste platinum catalyst in this embodiment differs from the method for separating platinum metal from waste platinum catalyst in the following ways:
[0093] The mixed leaching agent comprises 1.0 mol / L hydrochloric acid, 0.45 mol / L sodium sulfite, and 0.25 mol / L citric acid.
[0094] Example 5
[0095] The fifth embodiment of the present invention provides a method for separating platinum metal from waste platinum catalyst. The method for separating platinum metal from waste platinum catalyst in this embodiment differs from the method for separating platinum metal from waste platinum catalyst in the following ways:
[0096] The amount of modified MOF material added was 4g.
[0097] Example 6
[0098] The sixth embodiment of the present invention provides a method for separating platinum metal from waste platinum catalyst. The method for separating platinum metal from waste platinum catalyst in this embodiment differs from the method for separating platinum metal from waste platinum catalyst in the following ways:
[0099] The amount of modified MOF material added was 6g.
[0100] Example 7
[0101] The seventh embodiment of the present invention provides a method for separating platinum metal from waste platinum catalyst. The method for separating platinum metal from waste platinum catalyst in this embodiment differs from the method for separating platinum metal from waste platinum catalyst in the first embodiment in that:
[0102] The pH value for adsorption is 2.
[0103] Example 8
[0104] The eighth embodiment of the present invention provides a method for separating platinum metal from waste platinum catalyst. The method for separating platinum metal from waste platinum catalyst in this embodiment differs from the method for separating platinum metal from waste platinum catalyst in the following ways:
[0105] The pH value for adsorption is 3.
[0106] Example 9
[0107] The ninth embodiment of the present invention provides a method for separating platinum metal from waste platinum catalyst. The method for separating platinum metal from waste platinum catalyst in this embodiment differs from the method for separating platinum metal from waste platinum catalyst in the following ways:
[0108] The amount of hydrazine hydrate added was 0.5g.
[0109] Example 10
[0110] The tenth embodiment of the present invention provides a method for separating platinum metal from waste platinum catalyst. The method for separating platinum metal from waste platinum catalyst in this embodiment differs from the method for separating platinum metal from waste platinum catalyst in the first embodiment in that:
[0111] The amount of hydrazine hydrate added is 1g.
[0112] Example 11
[0113] The eleventh embodiment of the present invention provides a method for separating platinum metal from waste platinum catalyst. The method for separating platinum metal from waste platinum catalyst in this embodiment differs from the method for separating platinum metal from waste platinum catalyst in the first embodiment in that:
[0114] The pulsed electric field strength is 12 kV / m.
[0115] Example 12
[0116] The twelfth embodiment of the present invention provides a method for separating platinum metal from waste platinum catalyst. The method for separating platinum metal from waste platinum catalyst in this embodiment differs from the method for separating platinum metal from waste platinum catalyst in the first embodiment in that:
[0117] The pulsed electric field strength is 18 kV / m.
[0118] Comparative Example 1
[0119] The first comparative example of the present invention provides a method for separating platinum metal from waste platinum catalyst. The method for separating platinum metal from waste platinum catalyst in this comparative example differs from the method for separating platinum metal from waste platinum catalyst in the first embodiment in that:
[0120] Remove citric acid from the mixed leaching agent.
[0121] Comparative Example 2
[0122] The second comparative example of the present invention provides a method for separating platinum metal from spent platinum catalyst. The method for separating platinum metal from spent platinum catalyst in this comparative example differs from the method for separating platinum metal from spent platinum catalyst in the first embodiment in that:
[0123] Replace UiO-66-ATU with UiO-66-NH2.
[0124] Comparative Example 3
[0125] The third comparative example of the present invention provides a method for separating platinum metal from spent platinum catalyst. The method for separating platinum metal from spent platinum catalyst in this comparative example differs from the method for separating platinum metal from spent platinum catalyst in the first embodiment in that:
[0126] Single ultrasonic leaching.
[0127] Please refer to Table 1 below, which shows the parameters corresponding to the above embodiments and comparative examples of the present invention. The platinum leaching rate was determined using inductively coupled plasma atomic emission spectrometry (ICP-AES). Digestion solutions and leachates of the original waste catalyst samples were prepared separately, and the Pt element concentration was quantitatively analyzed to calculate the leaching rate. The platinum recovery rate was calculated by weighing the final platinum powder mass and the total platinum mass calculated from the leachate. Platinum purity was analyzed using ICP-MS (inductively coupled plasma mass spectrometry).
[0128] Table 1
[0129]
[0130] According to the data from the examples, the ternary components (hydrochloric acid, sodium sulfite, and citric acid) of the mixed leaching agent need to be synergistically adjusted. Parameters such as the amount of UiO-66-ATU added, adsorption pH, hydrazine hydrate dosage, and pulse electric field intensity need to be precisely matched. Deviation from the optimal range will lead to impaired recovery performance.
[0131] Comparative studies have verified that citric acid is key to protecting the support and improving adsorption selectivity; the ATU ligand of UiO-66-ATU is the core to achieve specific adsorption of Pt(IV); and the synergistic effect of ultrasound and pulsed electric field is a necessary condition for enhancing mass transfer and ensuring leaching efficiency. The absence or replacement of these technologies will significantly reduce the recovery efficiency.
[0132] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0133] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.
Claims
1. A method for separating platinum metal from spent platinum catalyst, characterized in that, The method includes: Waste platinum catalyst is pulverized to 80-120 mesh and calcined at a first preset temperature to remove surface organic matter, thus obtaining waste platinum powder. Waste platinum powder is added to a mixed leaching agent according to a preset solid-liquid ratio. The leaching temperature is adjusted under an ultrasonic-pulse electric field environment, and the solution is filtered to obtain a leachate. The mixed leaching agent includes hydrochloric acid, sodium sulfite, and citric acid. Modified MOF material was added to the leachate to adjust the pH value, adsorb platinum ions, and then filtered to obtain filter residue. The filter residue is added to the desorption solution for analysis, filtered, and hydrazine hydrate is added to the filtrate. The filtrate is then reduced at a second preset temperature, and solid-liquid separation is performed to obtain sponge platinum. The desorption solution includes thiourea and hydrochloric acid. The platinum sponge was washed with dilute nitric acid and dried under vacuum to obtain platinum powder. Among them, the modified MOF material includes UiO-66-ATU, and its preparation method includes: Add 5g~15g of UiO-66-NH2 to 450mL~550mL of DMF according to the solid-liquid ratio and disperse ultrasonically for 20min~40min to obtain a suspension. Add 2g~5g of 3-aminothiourea and 0.5g~3g of N,N'-dicyclohexylcarbodiimide to the suspension, and stir the mixture at 50℃~70℃ for 100rpm~200rpm for 6h~10h. Filter the mixture and wash the filter cake three times alternately with DMF and anhydrous ethanol. UiO-66-ATU was obtained by drying at 50℃~70℃ for 10h~15h.
2. The method for separating platinum metal from spent platinum catalyst according to claim 1, characterized in that, The first preset temperature is 150℃~200℃, and the calcination time is 40min~60min.
3. The method for separating platinum metal from spent platinum catalyst according to claim 1, characterized in that, Waste platinum powder is added to a mixed leaching agent according to a preset solid-liquid ratio. Leaching is performed under an ultrasonic-pulsed electric field environment, with the leaching temperature adjusted. The mixture is then filtered to obtain a leachate. The mixed leaching agent comprises hydrochloric acid, sodium sulfite, and citric acid. Specifically, the process includes: Waste platinum powder is added to the mixed leaching agent according to a preset solid-liquid ratio and stirred evenly. The mixed leaching agent includes 0.8mol / L~1.2mol / L hydrochloric acid, 0.4mol / L~0.6mol / L sodium sulfite, and 0.2mol / L~0.4mol / L citric acid. The solvent is water, and the preset solid-liquid ratio is 1g:(10~15)mL. The solution is then added to a coupled reactor that integrates an ultrasonic generator and a high-voltage pulse power supply. It is then leached for 30 to 50 minutes under an environment with an ultrasonic power of 250W to 350W, a pulse electric field strength of 12kV / m to 18kV / m, a pulse frequency of 40Hz to 60Hz, a leaching temperature of 50℃ to 70℃, and a stirring rate of 150rpm to 250rpm. The solution is then filtered to obtain the leachate.
4. The method for separating platinum metal from spent platinum catalyst according to claim 1, characterized in that, The solid-liquid ratio of the modified MOF material to the leachate is 1 g: (0.1~0.4) L, the pH value is 2~3, and the pH value adjuster is hydrochloric acid.
5. The method for separating platinum metal from spent platinum catalyst according to claim 4, characterized in that, The adsorption step includes: Placed in a constant temperature oscillation environment, adsorbed for 40 min to 60 min at a oscillation rate of 200 rpm to 250 rpm at a temperature of 20 ℃ to 40 ℃.
6. The method for separating platinum metal from spent platinum catalyst according to claim 1, characterized in that, The mass ratio of the filter residue to the desorption solution and hydrazine hydrate is 1:(20~45):(0.05~0.2). The desorption solution includes 0.05mol / L~0.2mol / L hydrochloric acid and 0.1mol / L~0.5mol / L thiourea, and the solvent is water.
7. The method for separating platinum metal from spent platinum catalyst according to claim 6, characterized in that, The desorption step includes: Desorption was carried out by stirring at 30℃~40℃, with a stirring rate of 150rpm~250rpm and a stirring time of 20min~30min.
8. The method for separating platinum metal from spent platinum catalyst according to claim 6, characterized in that, The second preset temperature is 60℃~80℃, the reduction time is 20min~50min, the reduction stirring rate is 150rpm~250rpm, and the solid-liquid separation conditions are centrifugation at 2500rpm~3500rpm for 4min~10min.
9. The method for separating platinum metal from spent platinum catalyst according to claim 1, characterized in that, The concentration of dilute nitric acid is 3wt%~7wt%, and the vacuum drying conditions are vacuum drying at 70℃~90℃ for 1.5h~3h.